The present invention provides a formulation for use in the treatment of corrosion and metal sulphide scale deposits in aqueous systems, said formulation comprising a tetrakis (hydroxyorgano) phosphonium salt (THP+ salt) and a primary, secondary or tertiary alcohol having an acetylenic bond in the carbon backbone. The invention also provides the use of such a formulation for treating corrosion of mild steel, copper or aluminium, and a method for treatment of an aqueous system containing or in contact with a metal sulphide scale while concomitantly inhibiting the corrosion of surfaces in contact with said aqueous system, which method comprises the addition to said aqueous system of a scale and corrosion inhibiting amount of such a formulation.